This invention is concerned with laser diodes and more specifically with the efficient generation of three, four or five intersecting laser beams which are mutually orthogonal. These beams are used in alignment applications where the beams represent reference lines. Other beam generators are described in U.S. Pat. Nos. 5,500,524 and 5,617,202 assigned to the assignee of this invention and the disclosures of those patents are incorporated by reference in this application.
Generally, visible laser diodes have a much wider divergence in the direction perpendicular to the junction than that parallel to the junction. Typical values are 35.degree. in one axis and 10.degree. in the other. Normally, the central zone or portion of the beam is apertured to produce a beam which is nearly round, cropping a portion of the beam's power. If other beams are required, a beam splitter and subsequent optics are used to manipulate the newly created beam. The present invention in one embodiment uses the elliptical or oblong shape of the collimated beam from a diode laser to generate three parallel beams, which can subsequently produce five beams of light by using partial reflection and transmission. The beams form an xyz coordinate system which can be used as reference lines. A collimated laser beam which is not necessarily oblong can be used to produce multiple reflected beams using reflective surfaces positioned at different portions of the path of the collimated beam. One beam can be generated simply by transmission, without reflection.
According to the invention, the basic method used to generate orthogonal and intersecting alignment laser beams includes collimating the laser beam from a laser diode, then reflecting portions of the beam and in some embodiments transmitting a portion of the beam. To achieve the precise beam angles required, the angles between the normal to the reflector surfaces and the transmitted beams must be 45.degree.. This angular relationship will become clear from the drawings. The beam angle relative to the reflectors must be adjusted to achieve accuracy in the resulting instrument. This may be done by tipping the reflector or by adjusting the position of the collimating lens.